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Simple Blood Test Tracks Tumor Evolution in Cancer Patients

Scientists develop new way to detect drug resistance (May 2)

By tracking changes in patients’ blood, scientists at the University of Cambridge in the U.K. have created a new way of looking at how tumors evolve in real time and develop drug resistance. The research was published in the May 2 print edition of Nature.

The researchers used traces of tumor DNA, known as circulating tumor DNA (ctDNA), found in cancer patients’ blood to follow the progress of the disease as it changed over time and developed resistance to chemotherapy treatments.

They followed six patients with advanced breast, ovarian, and lung cancers and took blood samples over 1 to 2 years. They then focused their analysis on samples that contained relatively higher concentrations of ctDNA.

By looking for changes in the ctDNA before and after each course of treatment, the researchers could identify changes in the tumor’s DNA that were likely linked to drug resistance following each treatment session.

Using this method, they were able to identify several changes linked to resistance to chemotherapy drugs, such as paclitaxel (Taxol, Bristol-Myers Squibb), which is used to treat ovarian, breast, and lung cancers; tamoxifen, which is used to treat estrogen-positive breast cancer; and trastuzumab (Herceptin, Genentech), which is used to treat HER2-positive breast cancer.

The researchers hope that this new approach will facilitate research on how cancer tumors develop resistance to some of the most effective chemotherapy drugs, as well as provide an alternative to current methods of collecting tumor DNA by taking a sample directly from the tumor — a much more difficult and invasive procedure.